The invention concerns a dosing device for liquids suited to be applied to the output hole of containers and to be used for the dosing of liquids, mostly for domestic usage like detergents, oils and chemical products to be used in predeterminate amounts.
The need for the chemical industry to produce containers equipped with dosing devices is due to the necessity to optimize the performances of the product contained therein and also to avoid a misuse of the product which, on the one hand, controlled lead to worse results than those obtainable with a controlled dose, and On the other hand could lead to ecological problems due to environmental pollution. For these reasons dosing devices for liquids are a more and more frequent industrial choice.
Dosing devices are known consisting of outlets provided with channels inside which a sphere slides, immersed in the liquid to be dosed and running along a predeterminate distance. When the container is turned upside down from the upright position to the liquid output position, the liquid keeps outflowing as long as the sphere moves toward the output hole until the sphere closes it. This kind of device is described in DE-C-93250. The main disadvantage arising from such devices is that the stroke of the spheres depends on the density of the liquid in which the spheres are immersed, thus the weight of said spheres must be changed according to the density of the liquid to be poured out. Therefore, it is necessary either to change the material the spheres are made of, or to change the size of the spheres, with the obvious disadvantages arising from the realization of dosing devices of different sizes. Further, it must be noted that these types of dosing devices are not very precise, because the speed of the sphere in the closing phase depends also on the liquid head which overhangs it, and therefore, as the container is discharged, the amount of liquid which is delivered by the dosing device varies itself.
DE3715617-A discloses a sealing cap with a dispenser system axially movable with a thread, but there is not a slidable dosage member between said dispenser system and the external part of the cap.
U.S. Pat. No. 1,687,705 discloses a dispensing device in which the dosing chamber does not itself slide, but a sliding ring valve moves along the outer surface of a fixed dosing chamber.
The international patent application PCT/EP90/02106 filed by the same inventor concerns a dosing device comprising an essentially tubular external body, a sliding dosing element inserted in the external body, a co-axial output duct placed inside the external body and a predosing chamber for the liquid placed between the internal surface of the external body and the external surface of the output duct. After the preselected dose has reached the sliding dosing element, the reversal of the container from the upright position to the overturned position makes the dosing element to slide toward the outside, so as to close the communication between the inside of the container and the output duct, while the liquid contained in the dosing element is ejected outside and the liquid contained in the container enters the predosing chamber.
This device overcomes the above mentioned disadvantages, but it presents some difficulty in the construction, because to the three above mentioned elements, i.e. the internal body, the external body, and the sliding dosing element, a connection element is necessarily required between the external body and the neck of the container, which comprises the cap too. Basically, the dosing device of the above mentioned invention consists of four parts separately moulded and then assembled.